1. Technical Field
The present invention relates to charging devices, and more particularly to a multi-port charging device that is able to charge multiple electronic devices simultaneously, to show real-time charging states, and to set charging currents.
2. Description of Related Art
Portable electronics are widely used in every level of our daily life. Taking data-accessing applications for example, the heavy printed documents can now be saved electronically for convenient and rapid access anytime, anywhere by using such as e-books, tablet computers, notebooks, smart phones and so on. Theses electronics are generally powered by rechargeable batteries contained therein.
For leveraging the advantage of portable electronics, many schools and organizations have replaced the traditional printed books with some of the above-mentioned devices, and particularly, with e-books. It is known that e-books need to be charged once a day if not more frequently for continuous operation. In a school scenario, it is more preferable to charge students' e-books simultaneously, for example, after school. However, it is often seen that the e-books are left overnight with the charger connected thereto and since the traditional charger is typically unable to tell whether the battery in the connected e-book is fully charged, electric current keeps running between the charger and the e-book as long as they are connected. Such a charging practice, over time, can cause damage to the components in the e-book and shorten the service life of the e-book, and can also be harmful to the charger itself. Another defect of the traditional charger is the lack of the function of identifying the real-time charging states. With this defect, a user is unable to know whether the charged device is sufficiently charged, and can be put in an awkward plight where he/she spends much time to wait for the device booting and finally recognizes that the remaining power level is not sufficient for the entire coming class. While some manufacturers therefore have developed some external instrument to be connected to the traditional charger for detecting the charging status of the charged electronic devices, the external instrument means additional costs and additionally burdensome operation. On the other hand, there are existing chargers equipped with indicator lamps for showing that charging is going on and that the battery is fully charged, but these existing chargers are unable to show the remaining power level through the lamps, so the user has no way to learn whether the battery is almost fully charged or is in an extremely low power state. There are even cases where an e-book or an electronic device is not properly connected to a charger and thus is not getting charged, but the charger still lights up its “charging” lamp. In these cases, the “charging” time is wasted in vain.
Hence, there is a need to address the shortcomings of the traditional and existing chargers by allowing a user to easily and rapidly identify real-time charging states of charged devices, so as to save power and protect electronics to be charged.